The present invention relates to the conveyor art and, more particularly, to an improved split housing for at least partially covering a drive or idler sprocket in a conveyor system.
Today, in many modem. manufacturing facilities, modular conveyor systems are extensively utilized to transport articles to and from various work stations during all stages of production. In recent years, manufacturers using production lines with conveyors as an integral component of the material handling system have realized reasonably significant gains in productivity and resource utilization. As a result, modular conveyor systems have become even more widely implemented and have been adapted to meet an even wider scope of the material handling needs of producers of a multitude of consumer and industrial goods. Therefore, the continual development of improved modular conveyors is necessary in order to keep pace with the demands and expectations of the users of such conveyors.
Conventional conveyor systems employing endless, modular link or roller chain belts are typically driven at one end of an elongated guide structure, such as a rail or the like, by a sprocket coupled to a rotating shaft. The shaft is in turn rotated by a motive device, such as a variable speed electric motor. At the opposite end of the guide structure, an idler sprocket for engaging the belt is coupled to an idler shaft. As should be appreciated, the drive and idler sprockets assist in supporting and guiding the endless belt as it makes the transition from the forward run to the return run, or vice versa, at each respective end of the guide structure.
Of course, both the drive and idler sprockets are subject to wear as a result of the substantially continuous engagement maintained with the conveyor belt. If not kept in check, this wear may affect the overall performance of the conveyor system. For example, a worn sprocket may allow the belt to slip, which creates both timing and efficiency problems. Hence, it is necessary to perform an inspection of the sprocket(s) from time to time to determine whether some form of ameliorative action, such as a repair operation or perhaps even a complete replacement, is required.
While inspection may only require removing the belt to gain visual access to the sprocket, a repair operation or a complete replacement requires removing the sprocket from the corresponding support shaft altogether. In the case where a single unhoused drive or idler sprocket is carried on the shaft, removing the belt and the sprocket is a relatively uncomplicated undertaking. However, in the situation where a plurality of sprockets are gang driven or carried on a single support shaft, removing any of the inner sprockets becomes a time and labor intensive process, since all adjacent outer sprockets and any other corresponding structures (side plates, chain guides/strippers, conveyor frame components or other support structures, etc.) must first be removed. As should be appreciated, removing even a portion of the sprockets significantly increases the time and labor involved. Additionally, the wholesale removal and replacement of multiple sprockets carried on a shaft may create alignment and/or timing problems that must be corrected to ensure efficient operation. Of course, the time and labor required to remedy these problems further exacerbates the situation.
In some conveyor systems, it is also desirable to employ a sprocket housing. An example of a housing arrangement for a sprocket used in a roller chain conveyor system may be found in U.S. Pat. Nos. 5,314,059 and 5,311,983, both the Clopton. As should be appreciated, the use of such a sprocket housing is generally advantageous, since it not only covers and protects the sprocket from external interference, but also provides a guiding function for the belt as it transitions along and is engaged by the sprocket.
Despite generally providing the limited advantages described above, it can easily be appreciated that the use of a housing, such as the one disclosed in the above-referenced patents, serve as yet another obstacle to easily accessing or removing the sprocket. Specifically, since the housing is divided into left and right halves through which the shaft for supporting the sprockets extends, extra effort is required to completely remove the sprocket from the shaft. The amount of effort required is greater in the case where a plurality of sprockets are coaxially mounted, since any adjacent sprockets and/or housings must first be removed. Also, since each portion of the split housing is connected directly to the adjacent guide rail, it is also necessary to remove any fasteners or connectors used to secure the adjacent housings to the guide rails prior to removing the sprocket. This significantly increases the time and expense required for performing even a cursory inspection of a single sprocket to determine whether replacement is warranted.
Another consideration in extending the service life of most driven conveyor belt systems is reducing friction. In the past, many proposals have focused on providing sprocket housings that support the shafts on active bearing elements or, more recently, bearing surfaces formed of materials having enhanced resistance to wear and beneficial tribological characteristics (e.g., ultrahigh molecular weight (UHMW) plastics). Even with the use of such specialized materials, supplying additional lubrication is often desirable to ensure that the drive and/or idler shafts freely rotate relative to the housings and create only a modicum of wear. However, in many conveyor systems, and especially those employed for conveying food products or the like, the operator must be careful in applying the lubricant to avoid potentially creating a contamination hazard. Hence, eliminating the need for external lubrication in conveyor systems where a modular link or roller chain conveyor belt is guided by or through a sprocket housing in making the transition from the forward to the return run in the conveyor system, or vice versa, is desirable.
Accordingly, the foregoing discussion clearly identifies the particular need for an improved manner of housing one of the drive or idler sprockets in a conveyor system. By splitting the housing into first and second portions in a novel manner, it would be possible to mount the first portion independently of any guide rail or structure supporting the second portion. Hence, the second portion could remain attached to a stable structure at all times while the first portion is fully or partially removed. This would permit one performing an inspection to gain full access to the sprocket and adjacent shaft without requiring the removal of the portion attached to the stable support structure, any adjacent sprockets, or other structures. The optional use of a split sprocket would also further enhance the efficiency of the repair or replacement operation, and again without any significant disruption to the overall conveyor system. Likewise, the optional use of an internal lubricant source in the housing would ensure that the desired low friction rotation of the support shaft is achieved without the need for externally applying a lubricant and, in the case where food products are being conveyed, risking contamination. Overall, this combination of features would result in an conveyor system that is a significant improvement over those proposed in the past, especially in terms of maintenance cost and efficiency.
In accordance with a first aspect of the present invention, an apparatus for at least partially covering a sprocket and assisting in guiding a conveyor belt in making a transition from a guide rail over the sprocket (or vice versa) is disclosed. The apparatus comprises a housing split into mating first and second portions. The housing at least partially covers the sprocket and includes a first guide track for guiding the belt along the transition and over the sprocket. As a result of the split in the housing, at least one of the first or second portions may be removed in a vertical direction without moving the sprocket in the housing or the guide rail.
In one embodiment, the first portion of the housing is an upper portion and the second portion of the housing is a lower portion. These upper and lower portions together define a first aperture for receiving a shaft for supporting the sprocket. The lower portion of the housing may include at least one reservoir adjacent to the first aperture for holding a lubricant for lubricating the shaft. A wick in the reservoir may provide the desirable wicking action to ensure that the lubricant is delivered from the reservoir to adjacent the shaft. The lower portion of the housing may also include a receiver for receiving a stable support structure, such that the upper portion of the housing may be removed while the lower portion remains fully supported by the stable support structure.
A portion of the first guide track in the housing may include an opening for allowing one or more teeth on the sprocket to engage the passing belt. Preferably, the first portion of the housing includes the first guide track and the second portion of the housing includes a second guide track for aligning with the first guide track to define a substantially continuous guide surface. At least a portion of the second guide track may include a second opening for allowing one or more teeth of the sprocket to engage the passing belt.
One of the first or second portions of the housing may include at least one boss that engages a corresponding emboss on the opposite portion. The mating boss and emboss assist in achieving proper alignment of the first and second portions. The first and second portions may also be secured by at least one fastener. The fastener preferably extends through an aperture in the first portion into a bore in the second portion.
In one embodiment, the modular link conveyor belt includes a plurality of interconnected links, with each link having a pair of depending arms. Each depending arm carries an inwardly projecting guide tab. The first guide track includes first and second lips for engaging the respective guide tabs as the conveyor belt passes. Preferably, the lips project outwardly in an opposed fashion.
In accordance with a second aspect of the invention, a conveyor system comprising at least one endless conveyor belt having a forward run for moving articles from one location to another and a return run is disclosed. The system further comprises at least one driver including a first sprocket for driving the belt, at least one guide rail for guiding the forward and return runs of the belt, a second sprocket for assisting the belt in making a transition from one of the forward run or the return run of the at least one guide rail, and at least one housing for at least partially covering one of the first or second sprockets. The housing is split into mating first and second portions and includes a first guide track for guiding the conveyor belt over the corresponding first or second sprocket. At least one of the portions of the housing may be removed in a vertical direction without moving the sprocket corresponding to the housing or the guide rail.
In one embodiment, the first portion of the housing is an upper portion and the second portion of the housing is a lower portion. The lower portion may include a receiver for receiving a stable support structure. Accordingly, the upper portion of the housing may be removed while the lower portion remains supported by the stable support structure.
Preferably, the guide rail is in the shape of an I-beam and includes upper and lower guide tracks for guiding the belt along the respective forward and return runs. The upper guide track of the guide rail may be aligned with the first guide track of the housing to create a continuous guide surface for the belt as it transitions from the forward run to the return run, or vice versa. The second portion of the housing may also include a second guide track for assisting the belt in making the transition to the corresponding forward or return run. Hence, the upper guide track of the guide rail may be aligned with the first guide track of the housing and the lower guide track of the guide rail may be aligned with the second guide track of the second portion of the housing to create a continuous guide surface for the belt.
A shaft for supporting the first or second sprocket in the housing is also provided. Preferably, the first or second sprocket is a split sprocket comprised of at least two mating portions that couple over the support shaft. Hence, upon separating the first and second portions of the housing, full access is provided to one of the mating portions of the split sprocket for inspection or removal.
The first and second portions of the housing in the mated position may together define a first aperture for receiving a shaft for supporting the first or second sprocket. The first portion of the housing is preferably a lower portion and includes at least one reservoir adjacent to the first aperture for holding a lubricant for lubricating the shaft. A wick for placement in the reservoir serves to wick the lubricant to a position adjacent the shaft.
In one embodiment, the modular link conveyor belt includes a plurality of interconnected links. Each link includes a pair of depending arms, with each arm carrying an inwardly projecting guide tab. The first guide track includes first and second lips for engaging the guide tabs of the conveyor belt. Preferably, the lips project outwardly in an opposed fashion.
In accordance with a third aspect of the invention, a method for accessing a sprocket carried on a support shaft for assisting a conveyor belt in making the transition from a forward to a return run along a guide rail in a conveyor system is disclosed. The method comprises: (1) placing the sprocket in a split housing having mating first and second portions; (2) removing one portion of the split housing in a vertical direction without moving the sprocket or the guide rail. The first portion may be an upper portion and the second portion may be a lower portion, and the removing step may include removing the upper portion. Also, the sprocket may be a split sprocket comprised of at least two portions, and the method may include removing at least one portion of the split sprocket after removing the first portion of the split housing.